School may be out for summer, but it's never too late for a quiz – especially when the answer could help determine the results of the next election. So, here goes. Which has gone up more in the five years since the financial crisis began: wages or food prices? The answer, as everyone who's been near a shop since the collapse of Northern Rock surely knows, is food. Food prices, as measured by the Office for National Statistics's CPI measure, have shot up 28.7% since August 2007. Average weekly pay on the other hand has increased by less than 10%.

Food is not the only necessity that has become vastly more expensive in the past five years of economic turmoil. What the statisticians refer to as "electricity, gas and other fuels" has rocketed 45.5% in price. And transport costs have jumped by nearly 25%. For most British families, their lives during the past half-a-decade of financial turbulence has been marked less by toxic credit instruments or billowing Spanish borrowing costs, than by this drastic squeeze in living standards. The head of the Bank of England, Mervyn King, was spot on when he warned last year of the biggest such squeeze in living memory. Those huge jumps in the cost of groceries and household heating, compared to the meagre rises in pay, sadly bear out his observation.

Think about those long-term trends while scanning this morning's coverage of the latest inflation figures, because you will scarcely see much mention of them. Two sports are played every time the Office for National Statistics updates its CPI and RPI measures. The first is to pick out the items of interest: the things that rose or dropped particularly sharply on the month. On that score, the latest report did not disappoint, with the observation that airfares soared 21.7% between June and July. The second game played by economists is to work out what this means for Threadneedle Street. Ever since the Bank's last inflation report, the smart money has been on Mr King and his fellow rate-setters cutting the key interest rate further to zero by the end of this year – and introducing another round of quantitative easing. Yesterday's inflation report doesn't make that an impossibility, but it probably means that the monetary policy committee will need to argue harder for any policy designed to stoke inflation – at a time when inflation is already above target. Because it is by no means certain that inflation will naturally subside over the next few months.

While price pressures are subdued at home, Britain has been importing its inflation over the last few years in the form of dearer food and energy prices. The latter are picking up nicely, thanks to the increased tensions in the Middle East (see the leader below for the latest instalment). But it is rocketing food prices that really threaten to throw out the calculations of Mr King and co. An incredible summer drought in the US has already prompted Washington to warn this week that prices for corn and other crops (and for the livestock that feed on those grains) will soar.

That adds another ingredient to what is already a pretty potent political cocktail. Take the row that began yesterday over rail fares, which are now set to go up another 6.2% come January. This parliament will see a £1,000 rise in the price of an annual season ticket from many parts of London's commuter belt.

The yearly ticket from King's Lynn will now costs £5,325, while travelling in from Newbury in Berkshire will set you back just over £5,003. An already unpopular coalition is now on course for a bloody nose from voters in commuting marginals in the south-east. There is much here for opposition parties to make mischief of. The chancellor has no problems cutting fuel duty, and is adamant that inflation is coming down. That logic makes yesterday's high RPI reading an aberration; and will surely lead calls for him to reduce the rise in train fares in the autumn statement. Either the chancellor makes a U-turn on rail fare policy soon – or he tells his fellow Conservative MPs just how they are to calm down commuting constituents.